PONA analysis

PONA analysis a method of analysis for paraffins (P), olefins (O), naphthenes (N), and aromatics (A). 

The reactor effluent was analyzed by on-line GC-analysis prior to condensation. Each reactor line was equipped with a HP 5890 GC with flame ionization detector (FID), interfaced with a PC for data handling and storage. The method of analysis, based on HP s PONA analysis, included all important hydrocarbons up to C,. Heavier components than this were only present in trace amounts, and were not analyzed. Research octane numbers (RON) were calculated from GC-analysis based on an adapted version of the method presented by Anderson et al. (5). The hydrogen yield was calculated from GC-analysis as the hydrogen balance over the reactor. 

Pyrolysis was carried out on a feed composed of a 50/50 mixture by weight of low-density polyethylene (LDPE) and hydrotreated FT wax. Yields are given in Table 13.2, showing a 385°C- - yield of 57.5 wt%. The yield for a broader lube feed, 343°C- -, was 66.0 wt%. While there was considerable 538°C- - in the feed to the pyrolyzer, there was little 538°C- - in the product, which is believed here to be advantageous for low cloud point. Oleflnicity in the pyrolysis overhead was 76 wt% by PONA analysis. The olefinic overhead liquids from the pyrolysis of both FT wax and LDPE/FT wax were analyzed using gas chromatography. This showed the cracked product to be almost entirely 1-normal olefins and normal paraffins. 

Typical conditions for semiregenerative catalytic reforming units are given below in table 1. In this table feed PONA analysis, H2/HC molar ratio and operation conditions are given. 

Plant performance is initially visualized by the results of PONA analysis. The composition of feed and reformate are given in figures 1 2. The data shown correspond to cycle No.5 of a Pt-Sn catalyst, and were taken from startup to 80 Blls/lbcat which represents around 365 days of operation. It can be seen that the feed is rich in parafines, with medium concentration of naftenics and low in aromatics. The reforming process yields an increase in the aromatics concentration and a considerable decrease in naftenics. It is also clear that the feed concentration varies during the cycle due to variations in the feed quality. 

Fig. 1. PONA analysis of feed. Cycle No.5 Pt-Sn catalyst CR unit.

FIGURE 13.33 Typical chromatogram for PONA analysis of a naphtha sample. (Reprinted with permission from Reference 96, Hewlett-Packard Co.)... 

L. E. Green and E. Matt, PONA Analysis by High Resolution Fused Silica Gas Chromatography, paper presented at 33rd Pittsburgh Analytical Conf., 1982. 

ASTM Method 3710 PONA Analysis Simulated Distillation... 

When simple Hquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

In summary, the terminology used for the identification of the various methods might differ. However, in general terms, group-type analysis of petroleum is often identified by the acronyms for the names PONA (paraffins, olefins, naphthenes, and aromatics), FIONA (paraffins, isoparaffins, olefins, naphthenes, and aromatics), PNA (paraffins, naphthenes, and aromatics), PINA (paraffins. 

The analysis of products was made in all the cases by FID-gas chromatography (Varian Mod. CX3400) equipped with a PONA column of 50 m and coupled to a workstation. 

The pyrolysis bottoms were then hydroisomerized to give a —22°C pour point, 4.4 cSt oil of 154 VI (Table 13.3). The overall 343°C- - yield, based on feed to the pyrolyzer, was 44 wt%. Adding the potential lube from oligomerizing the lighter olefinic product from the pyrolyzer would increase the 343°C- - yield to about 59 wt%. However, in this run, a significant amount of 343°C— was in the feed to the hydroisomerization step (10 wt% based on feed to the pyrolyzer). Had this been sent to oligomerization, the potential 343°C- - would be at 67 wt% (Figure 13.11), based on the PONA olefin analysis. 

For some liquid feedstocks such as naphthas, the componential composition is often obtained by gas chromatography (GC) and/or mass spectrometry (MS). For gas oils or heavier feedstocks, it is impossible to obtain the desired analysis. Paraffins, olefins, naphthenes, aromatics (PONA) grouping is sometimes used as a means of feed characterization. For gas oils. Bureau of Mines Correlation Index (BMCI) has been used as a parameter for feed characterization. Since the 1980s, nuclear magnetic resonance (NMR) spectroscopy has been used to characterize heavy feedstocks. 

For gas chromatographic analysis a 50 m PONA fused silica wall coated capillary column (BP-1) was applied in temperature-programmed mode (-50 to 220 °C) with flame ionisation detection (FID) of hydrocarbons. 

Oil samples (50-60 mg) containing surrogate diamondoid standards were separated using a Hewlett-Packard 6890 gas chromatograph equipped with a 50-m PONA methylsilicone column (0.20 mm I.D., 0.52 /rm film thickness) programmed at 35°C for 5 min followed by 4°C/min heating to 310°C. The GC was interfaced with a 5973-MSD for mass spectral analysis. 

A Hewlett-Packard 5890 gas chromatograph equipped with a 50-m PONA methylsilicone chromatographic column (0.20 mm I.D., 0.52 /im film thickness) was used to separate Ce-Cig hydrocarbons for stable carbon isotope analysis. The column was heated at 35°C for 15 min followed by programmed ramps at 1.5°C/min to 70°C (no hold time), 3°C/min to 130°C (hold 12 min), and 3°C/min to 300°C (hold 20 min) using helium carrier gas. Internal standards included hexene, 2,3-dimethylpentene, cA-octene, 1-nonene, and 1-octadecene. Effluent peaks from the column were combusted at 950°C to carbon dioxide and transferred through a Micromass Isochrom 2 interface (350°C) for analysis using a Micromass Prism mass spectrometer. Carbon dioxide was used as the reference standard. C15+ hydrocarbons were separated and analyzed using a similar procedure. 

Isotope data (6 in %o relative to the PDB belemnite standard) for C6-C14 n-alkanes are from whole oil analysis using PONA methylsilicone column. Precision of the measurement 0.2%o for each compound. Data for C15-C19 n-aUcanes and pristane and phytane are from DB-1 analysis of saturated hydrocarbon fractions using DB-1 column. 

Isotope data in %o relative to the PDB belemnite standard) are from whole oil analysis using PONA... 

Compositional information from gas chromatographic analysis is more definitive than distillation data. A naphtha composition is given in Table 1. The composition is given after the naphtha has been hydrotreated to lower concentrations of olefins and contaminants. Some of the paraffin isomers are lumped together in this particular analysis. The compositional information is often categorized into the classes of paraffins, olefins, naphthenes, and aromatics, and is called a PONA. The ease of reforming feedstocks has been correlated to the sum... 

Cooperative studies are underway in ASTM D02.04 to find a better test method for total olefins. Cooperative work has been done to validate new gas chromatographic methods that trap the olefins on silver nitrate impregnated traps. These include a gas chromatographic multi-dimensional procedure for oxygenates and paraffin, olefin, naphthene, aromatic (O-PONA) hydrocarbon types in petroleum distillates and a GC fast total olefins analyzer (FTO) method. The FTO method has the advantage that the analysis time is quicker. The O-PONA method is an expanded version of ASTM D5443 and... 

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